In acidizing or fracturing a well, large volume, high pressure pumps inject a treatment solution into a line leading to the well head generally referred to as a frac line. The solution is generally chemicals mixed in water or gel-water and sand. The sand acts as a propping agent such that when the pressure opens up the earth's strata, the sand keeps the strata open.
Logging is utilized in various wells which helps determine the effectiveness and necessity of stimulating the well with fracturing materials or acid materials to stimulate the flow of fluid from the well. Heretofore, radioactive material was coated on sand which was sterilized and mixed in the blender which mixes the fracturing material and flows into the lower pressure side of the pumps into the well. This causes contamination of the pumps such that the pumps cannot be used for other materials. The pumps become radioactively hot causing significant safety problems around the well in the handling of the radioactive material. In addition, this creates problems with amount of radioactive material placed in the well and gives uncontrolled and varying results in the logging process.
Further radioactive materials heretofore used in logging wells have half-lives of around 200 to 300 days which made the use of these materials undesirable because the well had to be shut in for several days because it was radioactively hot and could not have fluids flowing therefrom into the normal pipeline. In addition, it is difficult to pump the radioactive coated sand into the well except through the blender and treatment pumps without large quantities of liquids, such as water or gel water which dilutes the radioactive materials which make it difficult to receive accurate results.
Heretofore, attempts to log wells have been based on temperature readings which are difficult to use to determine the flow of fluid within the well since the temperature reading will not give accurate results of the flow of fluid behind the well casing.
Heretofore, since radioactive materials were coated on sand it was uneconomically feasible to pump the materials in the pressure side of the frac line to the well.